Marine type muffler



April 13, 1965 T. N. KELLY MARINE TYPE MUFFLER 2 Sheets-Sheet 1 Filed June 27, 1960 INVENTOR. THOMAS NKELLY BY 60 ATTORNEYS April 13, 1965 T. N. KELLY MARINE TYPE MUFFLER Filed June 27, 1960 2 Sheets-Sheet 2 PISA.

SOUND FREQUENCY G.P.S-

FIG.5.

EXHAUST TUBE B SILENCER EXHAU$T TUBE ALONE United States Patent 3,177,971 MARINE TYPE MUFFLER Thomas N. Kelly, Detroit, Mich, assignor to Aircraft Precision Products, Inc., Oak Park, Mich., a corporation of Michigan Fiied June 27, 1960, Ser. No. 38,911 2 Claims. (Cl. 181-52) The invention relates to noise suppressors and refers more specifically to a marine type muffler constructed to receive hot exhaust gases and fluid simultaneously and to cool the exhaust gases, suppress exhaust sound, and discharge the cooled gases and fluid without creating an undesirable back pressure.

An object of the invention is to provide an improved muffler construction for mixing hot exhaust gases and cooling fluid for rapid cooling of the gases.

Another object is to provide an improved mufiler for mixing hot exhaust gases and cooling fluid which muffler is constructed to maintain minimum back pressures.

Another object is to provide an improved muflier for mixing exhaust gases with cooling fluid including a plurality of acoustic filter sections for accomplishing noise suppression which muffler is constructed to reduce in ternally generated noises.

More specifically it is an object to provide improved muflier construction comprising a tubular housing having closures secured over both ends thereof and in cluding an inlet tube extending through the closure at one end of the housing in an upper portion of the muffler as installed and an exhaust tube extending through the closure at the other end of the housing in a lower portion thereof with respect to the muffler as installed.

Another object is to provide a muffler construction as set forth above wherein the inner end of the inlet tube is tapered axially inwardly of the tube, radially inwardly of the housing to provide uniform expansion of the gas and fluid introduced into the muffler.

Another object is to providea muffier construction as set forth above wherein the inner end of the exhaust tube is tapered axially inwardly of the tube, radially inwardly of the housing to provide for smooth escape of the exhaust gases from the muffler.

Another object is to provide a muflier construction as set forth above wherein the housing is divided into a plurality of resonant chambers for noise suppression by transverse partitions having ducts extending therethrough to connect adjacent chambers.

Another object is to provide a mufiier construction as set forth above wherein the ducts have diameters approaching or exceeding their length so that the ducts will not resonate as open pipes but will function as acoustic coupling ducts.

Another object is to provide a rnuflier as set forth above which is simple in construction, economical to manufacture and eflicient in use.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a longitudinal section of a mufiier constructed according to the invention.

FIGURE 2 is an end view of the mufiier taken on line 2-2 of FIGURE 1.

FIGURE 3 is a cross section of the muffler illustrated in FIGURE 1 taken on the line 3-3 in FIGURE 1.

FIGURE 4 is a graph showing the relative attenuation of different sound frequencies in a specific embodiment of the muflier of the invention.

FIGURE 5 is a graph showing typical back pressures 3,177,971 Fatented Apr. 13, 1965 at different percentages of rated load for mufflers constructed according to the invention.

With particular reference to the drawings a specific embodiment of the present invention will now be disclosed.

As shown best in FIGURE 1 the muflier 10 of the invention comprises a tubular housing 12, provided with closures 14 and 16 at opposite ends and which is divided into resonant chambers 18, 20 and 22 by partitions 24 and 26 located between the closures 14 and 16 at longitudinally spaced points of the housing 12. The partitions 24 and 26 have acoustic coupling ducts 28 and 30 respectively extending therethrough. An inlet tube 32 extends through closure 14 into the upper portion of the housing 12 of the installed muflier. Similarly an exhaust tube 34 extends through closure 16 into a lower portion of the installed muffler.

The muflier 10 constructed as shown is particularly adapted to receive a mixture of water and hot exhaust gases from an internal combustion engine. The muifler 10 is operable to further mix the water and gases to cool the exhaust gases. Muffler 10 is also constructed to suppress the exhaust noise and discharge the gases and water without creating objectionable back pressures.

More specifically the housing 12 comprises an elongated cylinder which may be constructed of relatively light weight corrosion resistant material such as titaniumstabilized stainless steel. Closures 14 and 16 which are similar in construction are secured over the opposite ends of the housing 12 by means of the annular flanges 36 and 38 respectively by convenient means such as weld 39 to provide a seal between the closures 14 and 16 and the housing 12.

As indicated best in FIGURE 1 the closure 14 has an opening 40 therethrough adjacent the periphery thereof through which the inlet tube 32 extends. The inlet tube 32 may be secured to the flange 42 around the opening 40 by convenient means for sealing the inlet tube 32 to the closure 14 such as weld 41. The inlet tube 32 is positioned adjacent the periphery of the closure 14 so that the exhaust gases and water may be introduced into an upper portion of the muffler 10 as installed.

The closure 16 is also provided with an opening 44 therethrough adjacent the periphery thereof. Flange 46 is provided around the opening 44 as shown in FIGURE 1 to which the exhaust tube 34 may be sealed by convenient means such as weld 47. The exhaust tube 34 as shown in FIGURE 1 extends through a lower portion of the closure 16 with respect to the muffler 10 as installed to facilitate discharge of gas and water from the mufiier 10.

The inner end 48 of the inlet tube 32 is tapered axially inwardly of the tube 32 radially inwardly of the housing 12 as shown. The tapered end of the inlet tube 32 provides uniform expansion of exhaust gas and water discharged into the chamber 18 therefrom to cause the gas and water to circulate within chamber 18 to most advantageously cool the gases and prevent generation of internal noises within the muflier.

The exhaust tube 34 is similarly provided with an inner end 50 which is tapered axially inwardly of the tube 34 radially inwardly of the housing 12. The tapered end 50 of the exhaust tube 34 permits smooth flow of the cooled exhaust gas and water from chamber 22.

Partitions 24 and 26 are circular as shown best in FIGURE 3 and include annular flanges 52 and 54 around the outer periphery thereof which are secured to the housing 12 as shown in FIGURE 1 by convenient means such as weld 55 to provide resonant chambers 18, 20 and 22 as previously indicated. It will be noted that the partitions 24 and 26 are spaced longitudinally of housing 12 so that the chambers 18, 20 and 22 have different dimensions and therefore resonate at different frequencies to produce sound attenuation as illustrated in FIGURE 4.

Partitions 24 and 26 are further provided with openings 56 and 58 in the lower portion thereof with respect to the installed mufiier and in line with the exhaust tube 34 as shown in the figures. Flanges 60 and 62 are provided about openings 56 and 58 in partitions 24 and 26 respectively to which the acoustic coupling ducts 28 and 30 are secured by convenient means.

Ducts 28 and 30 have diameters approaching their lengths as will be evident from inspection of FIGURE 1 whereby the ducts 28 and 30 will not resonate as open pipes but will function as acoustic coupling ducts to couple the sound from chamber 18 into chamber 20 and from chamber 20 into chamber 22.

The ducts 28 and 30 also serve to provide a path through the mufller from the inlet tube 32 to the exhaust tube 34 for the exhaust gases and water discharged into the muffler 10 which is substantially unimpeded so that a low back pressure is created by mufiler 10.

To insure complete drainage of water from muffler 10 the partitions 24 and 26 are each provided with a notch 64 at the lowest point thereof with respect to installed muffler for residual drainage of water from chambcrs 18 and into chamber 22. The exhaust tube 34 is also provided with a small opening 66 therein to permit residual drainage from chamber 22. Thus water is prevented from collecting in the mufiier 10 which might cause corrosion or damage due to freezing.

In operation it will be understood that the mufi ler 10 is connected with the inlet tube 32 positioned at the top thereof and the exhaust tube 34 positioned at the bottom. The muffler 10 may either be installed level or inclined slightly downwardly toward the exhaust tube 34 whereby gravity drainage of the water therethrough is possible. I A combined mixture of hot exhaust gases and water is discharged into chamber 18 through inlet tube 32. The hot gases and water are caused to expand uniformly on exit from the inlet tube 32 due to the tapered inner end thereof and are caused to intermingle in chamber 18 as indicated by the flow arrows 70 therein whereby the gas is caused to cool and the sound at the frequency to which the chamber 18 is tuned is suppressed.

The cooled gases and water together with the unsup pressed noise frequencies are passed intochamber 20 through acoustic coupling duct 28 wherein the gas and water are again mixed as indicated by the flow arrows 71 and the noise frequencies to which the chamber 20 is tuned are suppressed.

Similarly the cooled gas, water and unsuppressed noise frequencies from chamber 20 are passed into chamber 22 through acoustic coupling duct where the gases and water are again caused to mix as indicated by the flow arrows 72 and the remaining undesirable noise frequencies are suppressed. The cooled exhaust gas and Waterthen flow smoothly out of the exhaust tube 34 due to the location of the exhaust tube 34 in a lower portion of the mufiier and due to the tapered inner end of tube 34.

The muffler structure 10 of the invention is particularly efiicient in silencing the exhaust of internal combustion engines while producing a relatively low back pressure due to the alignment of coupling ducts 28 and 30 and the exhaust tube 34 in the lower portion of the muffler 10 and the positioning of the inlet tube 32 in the upper portion of the muffler 10 as shown in FIGURE 1 in conjunction with the tapered ends of the tubes 32 and 34. Typical back pressures for mufilers constructed in accordance with the invention having the relative proportions shown in FIGURE 1 are illustrated in FIGURE 5. It can be seen from the typical back pressure curves shown in FIGURE 5 that over the entire rated load typical mutfler back pressures vary between 0.40 and 0.60 pounds per square inch.

Similarly the efliciency of a particular embodiment of the mother 10 constructed .in accordance with the invention in suppressing noise frequencies between five hundred and four thousand cycles per second which are most objectionable is shown by the graph of FIGURE 4. From the graph of FIGURE 4 it can be seen that the noise frequencies between five hundred and four thousand cycles per second are attenuated as much as thirty-four decibels.

What I claim as my invention is:

1. A marine type muffler comprising an elongated tubular housing, separate inner and outer end headers respectively closing the opposite ends of said housing, a pair of transversely extending partitions secured Within said housing in longitudinally spaced relation to said end headers and to each other dividing said housing into first and second resonant chambers respectively adjacent said inner and outer end headers and a third resonant chamber between said first and second chambers, said third chamber being larger in volume than said second chamber and smaller in volume than said first chamber, an inlet tube extending through said inner end header into said first chamber, said inlet tube being disposed adjacent to the side wall of said tubular housing in laterally offset parallel relation to the longitudinal center line of said tubular housing, an acoustical coupling duct extending through and secured toone of said partitions, a second acoustical coupling duct extending through and secured to the other of said partitions, said ducts placing said chambers in communication with one another, an outlet tube extending through said outer end header into said second chamber, said outlet tube and said ducts being in spaced axial alignment with one another and disposed adjacent to the side wall of said tubular housing in laterally offset parallel relation to the longitudinal center line of said housing at the diametrically opposite side of said center line from said inlet tube, the end of said inlet tube within said first chamber lying in a plane inclined radially and axially inwardly relative to said housing at an acute angle to the longitudinal center line of said housing to provide for a uniform flow and expansion of exhaust gases and water into said first chamber, the end of said outlet tube within said second chamber lying in a plane inclined radially inwardly and axially outwardly relative to said housing at an acute angle to the longitudinal center line of said housing to provide for a smooth flow of exhaust gases and water from said second chamher, the arrangement of said tubes and ducts serving to reduce back pressure in the muffler, the ends of said ducts and the inclined ends of said tubes being open and unobstructed to further reduce back pressure.

2. The mufiler defined in claim 1, wherein said aligned outlet tube and ducts are vertically beneath the longitudinal center line of said housing and said inlet tube is vertically above the said longitudinal center line.

References Cited by the Examiner LEO SMILOW, Primary Examiner.

C. W. ROBINSON, ANTONIO F. GUIDA, Examiners.

a. awn 

1. A MARINE TYPE MUFFLE COMPRISING AN ELONGATED TUBULAR HOUSING, SEPARATE INNER AND OUTER END HEADERS RESPECTIVELY CLOSING THE OPPOSITE ENDS OF SAID HOUSING, A PAIR OF TRANSVERSELY EXTENDING PARTITIONS SECURED WITHIN SAID HOUSING IN LONGITUDINALLY SPACED RELATION TO SAID END HEADERS AND TO EACH OTHER DIVIDING SAID HOUSING INTO FIRST AND SECOND RESONANT CHAMBERS RESPECTIVELY ADJACENT SAID INNER AND OUTER END HEADERS AND A THIRD RESONANT CHAMBER BETWEEN SAID FIRST AND SECOND CHAMBERS, SAID THIRD CHAMBER BEING LARGER IN VOLUME THAN SAID SECOND CHAMBER AND SMALLER IN VOLUME THAN SAID FRIST CHAMBER, AN INLET TUBE EXTENDING THROUGH SAID INNER END HEADER INTO SAID FIRST CHAMBER, SAID INLET TUBE BEING DISPOSED ADJACENT TO THE SIDE WALL OF SAID TUBULAR HOUSING IN LATERALLY OFFSET PARALLEL RELATION TO THE LONGITUDINAL CENTER LINE OF SAID TUBULAR HOUSING, AN ACOUSTICAL COUPLING DUCT EXTENDING THROUGH AND SECURED TO ONE OF SAID PARTITIONS, A SECOND ACOUSTICAL COUPLING DUCT EXTENDING THROUGH AND SECURED TO THE OTHER OF SAID PARTITIONS, SAID DUCTS PLACING SAID CHAMBERS IN COMMUNICATION WITH ONE ANOTHER, AN OUTLET TUBE EXTENDING THROUGH SAID OUTER END HEADER INTO SAID SECOND CHAMBER, SAID OUTLET TUBE AND SAID DUCTS BEING IN SPACED AXIAL ALIGNMENT WITH ONE ANOTHER AND DISPOSED ADJACENT TO THE SIDE WALL OF SAID TUBULAR HOUSING IN LATERALLY OFFSET PARALLEL RELATION TO THE LONGITUDINAL CENTER LINE OF SAID HOUSING AT THE DIAMETRICALLY OPPOSITE SIDE OF SAID CENTER LINE FROM SAID INLET TUBE, THE END OF SAID INLET TUBE WITHIN SAID FIRST CHAMBER LYING IN A PLANE INCLINED RADIALLY AND AXIALLY INWARDLY RELATIVE TO SAID HOUSING AT AN ACUTE ANGLE TO THE LONGITUDINAL CENTER LINE OF SAID HOUSING TO PROVIDE FOR A UNIFORM FLOW AND EXPANSION OF EXHAUST GASES AND WATER INTO SAID FIRST CHAMBER, THE END OF SAID OUTLET TUBE WITHIN SAID SECOND CHAMBER LYING IN A PLANE INCLINED RADIALLY INWARDLY AND AXIALLY OUTWARDLY RELATIVE TO SAID HOUSING AT AN ANGLE TO THE LONGITUDINAL CENTER LINE OF SAID HOUSING TO PROVIDE FOR A SMOOTH FLOW AT EXHAUST GASES AND WATER FROM SAID SECOND CHAMBER, THE ARRAGEMENT OF SAID TUBES AND DUCTS SERVING TO REDUCE BACK PRESSURE IN THE MUFFLER, THE ENDS OF SAID DUCTS AND THE INCLINED ENDS OF SAID TUBES BEING OPEN AND UNOBSTRUCTED TO FURTHER REDUCE BACK PRESSURE. 